LlamaIndex

LlamaIndex is focused on connecting your data to LLMs. So you will see lots of features around this (retrieval algorithms, reranking, data loading, response synthesis)

Langchain is more of a kitchen sink library, trying to be and do everything

thanks for the reply, llama index fits perfectly for my rag application

also is there any fast vector database you can recommend?

i found qdrant to be fastest according to my test case

even though chroma client in present but i couldn't find any docs about it

Qdrant is probably the one I'd recommend 👍